Various techniques have been proposed for occupant protection devices that detect danger to a vehicle and protect a vehicle occupant, such as the technique described in Japanese Patent Application Laid-Open (JP-A) No. 2005-271889.
In the technique described in JP-A No. 2005-271889, it is proposed that a collision prediction determination is made based on the distance between a subject vehicle and a vehicle following to the rear, and when the distance measured is equal to or less than a predetermined value and it is predicted that a collision will occur after a predetermined time, and when the angle of the seatback is not equal to or greater than a predetermined value, the angle of inclination thereof is raised to a predetermined value and, in addition, the front edge of the seat cushion is lowered and, after the collision, the front edge of the seat cushion is raised.
However, in the technique described in JP-A No. 2005-271889, while the vehicle occupant is appropriately restrained by a seatbelt in preparation for a collision, there is a possibility that a high degree of restraint will be maintained when the dangerous situation is avoided, causing discomfort to the vehicle occupant. Accordingly, there is room for improvement of this technique.